1. Field of the Invention
This invention relates generally to headsets for sound reproduction, specifically headsets for accurately reproducing stereo sound and imaging, and, more particularly, to improvements in such stereo headsets, including expansion of the sound stage, and to solutions to some of the problems raised or not resolved thereby.
2. Description of the Related Art
Manufacturers of headsets have traditionally positioned the speaker elements either covering the ear, on the ear, or in the ear canal of the listener. These conventional placement methods create certain undesirable listening characteristics. Conventional headsets are often cited as being deficient in reproducing accurate stereo imaging and having limited sound stage. (The term xe2x80x9csound stagexe2x80x9d, as used in audio or video sound recordings, generally refers to the left-right spread of the sound between the speakers in a playback system. Thus the greater or more expanded the sound stage, the closer the resemblance to the real performance in the case of an orchestra or band recording playback, for example.) The stereo image produced by conventional headsets is often criticized for having poor spatial dimension, lacking xe2x80x9csound stagexe2x80x9d realism, and producing xe2x80x9csound in the middle of the headxe2x80x9d imaging. Prolonged listening with conventional stereo headsets may produce feelings of pressure or even a sensation of heaviness in the ears.
The inferior sound performance and discomfort which accompany conventional headset designs stem from the fact that such designs prevent either ear from receiving signals from the stereo channel directed to the other ear. Therefore, each ear hears only one stereo channel. This arrangement eliminates the subtle clues employed by the brain in determining the location of each sound""s point of origin, which are critical and essential to the accurate perception of stereo sound and imaging.
A headphone of the in-the-ear type has been proposed, in which a housing containing a speaker unit is inserted into the cavum concha of the listener""s ear. As is described in U.S. Pat. No. 5,519,782, issued to Shinohara et al., this type of headphone provides an arrangement whereby the speaker/acoustic transducer is partially inserted into the ear.
A headphone combining the vertical in-the-ear type headset and the conventional flat-against-the-ear type headset has been proposed, in which the in-the-ear first acoustic transducer is mounted at right angles to the flat-against-the-ear second acoustic transducer. As is described in U.S. Pat. No. 5,333,206, issued to Koss, this type of headset is worn such that when the second transducer is flat against the ear in a conventional manner, the in-the-ear first transducer extends into the cavum concha in the listener""s ear.
A conventional headset incorporating rotatable couplings between the earphone portions and the headband has been proposed, such that the earphone portions of the headset can rotate about the axis of the headband and thereby permit the headset to adapt to differently angled ears and also fold flat for more convenient transportation. As in the case of a headset with a single earphone, such an arrangement enables the earphone to be mounted adjacent either ear. As is described in U.S. Pat. No. 4,689,822, issued to Houng, this type of headset fails to address the deficiencies commonly encountered with conventional headset designs.
U.S. Pat. No. 3,900,707, issued to Hanson, provides a complex arrangement of mounted multiple speakers for enabling the reproduction of quadraphonic sound. A rather large and elaborate headgear is described having particularly-shaped cavities and particularly positioned speakers to introduce certain phase relationships in the sound that is reproduced. The overall size and complexity of the device described precludes its convenient and practical use and interferes with the activities and field of vision of the listener. In a word, this is a kluge. It does not address the problems solved by the present invention.
U.S. Pat. No. 4,027,113, issued to Matsumoto, et al. provides a coupling means for mounting the earcup to the headband portion of a conventional headset. The disclosed coupling means comprises a partial ball-and-socket mount to provide universal pivoting such that the earcup may fit and adapt to any type of ear. The listening effects provided by such design present all of the stereo imaging deficiencies encountered with conventional headset design.
A headset arrangement for holding the earphones flat against the ears is provided for in U.S. Pat. No. 3,919,501, issued to Cech et al. The against-the-ear arrangement provided therein fails to address the listening deficiencies commonly encountered with conventional headset design.
This invention relates to improvements to the stereo headset apparatus set forth above and to solutions to some of the problems raised or not resolved thereby.
The present invention comprises a stereo headset for use by a listener. Various arrangements in accordance with the invention enhance the quality of stereo sound and enable accurate stereo imaging through the proper placement and orientation of speakers relative to the ears of a listener. Accurate presentation of stereo sound and imaging, as well as expanded sound stage, is achieved through the proper positioning and orienting of the speakers rather than by means of audio propagation techniques or signal manipulation methods.
Particular arrangements of the present invention are effective in reproducing high-quality stereo sound and imaging and expanded sound stage through the application of principles of physics relating to sound and its properties. These arrangements project stereo sound waves from the speaker units to the ears of a listener under conditions of optimum angularity, embodying the ideal distance from the ear, and under controlled conditions in order to achieve stereo sound of superior quality with heightened image realism.
In accordance with the present invention, a speaker assembly is oriented at an angle to and spaced from the auditory canal rather than being generally in line therewith when the assembly is in place on the ear of the listener, as is commonly found in conventional headset designs. Through the configuration of the present invention, the speaker units may be positioned at optimum angles of incidence relative to the auditory canals of a listener such that the sound waves will diffract into the auditory canal. Furthermore, by providing adequate distance between the speaker assemblies and the listener""s ears, the present invention greatly heightens the stereo sound and imaging accuracy, thereby reducing the troubling stereo imaging phenomenon commonly encountered with conventional headset designs.
By increasing or decreasing the angle of the speaker units relative to the listener""s ear, the horizontal spatial dimension of the stereo sound may be narrowed or spread. This feature is not provided by any of the references cited herein.
The angle of projection of the speaker units of the present invention may be preset at a fixed angle generally suitable for most listeners, or each speaker unit may be adjustably mounted. Such adjustable mounting of the speaker units provides means by which angular adjustments may be performed by the listener to yield the most desirable stereo effect. For those who prefer the conventional flat-against-the-ear mode, such an orientation is provided by disclosed embodiments of the invention.
Angular adjustment means may comprise cross-axis pivoting joints, spline and shaft assemblies, ball and socket joints, and other variable positioning means. Such adjustable angular positioning means may be fixed or secured once the speaker units have been adjusted to the angle desired by the listener. Such angular adjusting means and securing means are well known in the art but, as used in connection with the disclosed embodiments of the present invention, constitute equivalent arrangements for the practice of the invention.
In marked contrast to conventional stereo headset design, the present invention positions the speaker units adjacent to the auricle of the listener""s ear without covering or obscuring the ear, such that the ear is located in the near field of the speaker units where sound clarity and imaging are most pronounced. Through this design, the stereo headset of the present invention avoids covering the auricle in order to prevent the head-in-a-barrel sensation, all the while permitting the free exchange of sound waves between the speaker units and both of the listener""s auditory canals. The speaker configuration and positioning of the present invention provide a more natural acoustical setting for the unrestricted dispersion of sound waves in marked contrast to conventional headset designs.